This study is designed to evaluate how well tumors respond to RSR13, an investigational drug that increases the amount of oxygen released from blood into the tissues, when given with radiation. Lack of oxygen in a tumor can reduce the effectiveness of radiation therapy; therefore, RSR13 may improve the effectiveness of radiation therapy by increasing oxygen delivery to the tumor. The safety of RSR13 will also be evaluated. The effectiveness of RSR13 in glioblastoma multiforme is not known. Radiation therapy is not experimental and is the standard treatment for glioblastoma multiforme. The RSR13 given in this study will be given with standard radiation therapy treatments. The main objective of this study is to evaluate how RSR13 affects the survival of patients with glioblastoma multiforme treated with standard radiation therapy. We will also evaluate the safety of repetitive daily intravenous doses of RSR13 that can be given with radiation therapy.